A stability and control-augmented vehicle

Abstract

A vehicle (2), such as a bicycle, motorbike, kick scooter or electric scooter, has a 5 vehicle body (4) and an upright steering column (12) having a front wheel (10) at its lower end, wherein the steering column is rotatable about a steering axis (14). A stabilising mass (20) is fixedly coupled to the steering column, the mass being in the range of 0.2 to 5.0kg, wherein the centre of gravity of the stabilising mass is spaced from the steering axis by a distance (X) in the range of 0.02 to 0.25m, and at a height 10 (h) above the ground in the range 0.1 to 1.5m. The stabilising mass acts to counter roll motion.

Description

[0001] Title: A Stability and Control-augmented Vehicle

[0002] Field of the disclosure

[0003] The present disclosure relates to a stability and control-augmented vehicle and is particularly directed at vehicles such as bicycles, motorbikes, kick scooters and electric scooters.

[0004] Background to the disclosure

[0005] Two-wheeled vehicles are inherently unstable, but can sometimes be stabilised at certain speeds to some extent by careful design of the steering geometry (caster angle and caster trail) and by the gyroscopic forces generated by the rotating wheels. Instability manifests itself in the yaw (directional instability) and in the roll modes, the latter of which can cause the rider to fall off.

[0006] Kick scooters and electric scooters are unstable at all speeds. This is due to the small wheels (low gyroscopic stabilising forces), and the standing rider, who is inadequately coupled to the vehicle. The mass of the scooter is 10 to 20kg or more, and the rider may be from 20 to over 100kg.

[0007] The reason a two-wheeled vehicle can be ridden at any speed relies on the skill and experience of the rider to provide a control system of adequate performance to stabilise it. In the case of scooters, the uncoupling of the masses of the rider and vehicle cause the unstable response of the vehicle to be at high frequency (around 5Hz), which the rider may find difficult to control, especially if their performance is degraded by alcohol, drugs, fatigue or distractions.

[0008] Humans are not bom with the inherent ability to either walk or ride a two-wheeled vehicle, and they are both skills that must be learned. Initially, a human responds to a sensory input indicating that they are off balance with a reaction time of 100ms to 250ms. During a 5Hz unstable mode, 100ms represents a phase lag of 180 degrees which will cause the instability to diverge, leading to a fall. This inability to control the instability of a scooter has led to a high number of accidents involving a single vehicle, where the rider falls off without striking another vehicle or pedestrian.

[0009] Some scooter designs employ a steer-centring spring arrangement, to make up for the lack of self-centring of the steering, caused by low caster and caster-trail. This is an expensive solution, with limited effectiveness.

[0010] Another approach is to provide a wide lateral foot platform, so that the rider can apply more roll control than the more usual fore-and-aft foot location. This adds cost and makes the scooter less practical.

[0011] Summary of the disclosure

[0012] The present disclosure provides a vehicle including: a vehicle body; an upright steering column having a front wheel rotatably coupled to its lower end, wherein the steering column is rotatable relative to the vehicle body about a steering axis; and a stabilising mass fixedly coupled to the steering column, the mass being in the range of 0.2 to 5.0kg, wherein the centre of gravity of the stabilising mass is spaced from the steering axis by a distance in the range of 0.02 to 0.25m, and at a height above the ground in the range 0.1 to 1.5m, and the stabilising mass is coupled to the steering column such that, when the vehicle experiences a roll acceleration to one side, the inertia of the stabilising mass causes a torque to be exerted on the steering column in a direction which urges the front wheel to turn towards the one side so as to counter the roll motion.

[0013] This concept is directed at two-wheeled vehicles and can be applied to any vehicle with two or more wheels arranged in a single line, whether powered or unpowered, such as a bicycle, motorbike, kick scooter or electric scooter. It can be implemented without requiring moving parts, electronics, or an energy source. It can also be low cost to manufacture and incorporate into a vehicle design. It can be retrofitted to existing vehicles to improve stability.

[0014] The stabilising mass is able to respond with no delay in order to stabilise the vehicle. The effect of the stabilising mass may largely correspond to the reaction of a skilled rider to unwanted roll, but occurs without any delay. A skilled / experienced rider uses feed-forward to minimise the delay, and so may not benefit from the presence of the stabilising mass, unless surprised by unwanted roll, or if their response is affected by other factors. An unskilled (learner) rider will benefit from the increased stability.

[0015] The stabilising mass increases the roll inertia of the vehicle, lowering the frequency of weaving oscillation of the vehicle. It also increases the inertia of the steering system, which reduces the amplitude and frequency of front wheel disturbances.

[0016] The steering torque applied by the stabilising mass is added to the rider’s steer torque inputs and does not affect their ability to control the vehicle through the steering.

[0017] The stabilising effect improves the vehicle stability during roll oscillation dynamic conditions. The inventors have determined that, due to the 90-degree (quarter-cycle) phase difference of acceleration, velocity, and displacement during an oscillation, the dynamic effect of the stabilising mass peaks at the start of an oscillation, when acceleration is greatest. This results in the stabilising effect damping the oscillation.

[0018] The increased stability makes it easier to learn to ride, more comfortable (less demanding) to ride, less prone to causing the rider to fall off, and therefore is safer.

[0019] The height of the centre of gravity of the stabilising mass, its spacing from the steering axis and the magnitude of the mass may be selected to give the optimum compromise between stability and control, and to provide the best position of the mass relative to the rider. The design and position of the stabilising mass should preferably be such that it cannot injure the rider in an impact or fall. For example, it may be mounted in such a way that its position can shift in an impact. The structure can be padded.

[0020] The vehicle body may comprise a rigid structure such as a platform or frame. A handlebar may be rigidly coupled to an upper end of the steering column. The centre of gravity of the stabilising mass may be located above the upper end of the steering column. In some examples, the stabilising mass may be located towards the upper end of the steering column and may at or around the same height as the handlebar or lower. A higher location will tend to increase the influence of the stabilising mass in countering a roll acceleration.

[0021] The stabilising mass may be fixedly coupled to the steering column in that it is fastened to the steering column. It may not be readily detachable by a user. For example, it may not be removable by hand. A tool may be required to remove the mass.

[0022] In an electrically powered vehicle, the stabilising mass may comprise a battery or batteries which may be part or all of the energy storage system for powering the vehicle. The batteries may be detachable for charging purposes. By using batteries of the vehicle to provide stabilising mass, rather than an additional mass, the overall weight of the vehicle may be reduced and the manufacturing cost may also be lowered.

[0023] The product of the magnitude of the stabilising mass, the distance between the centre of gravity of the stabilising mass and the steering axis, and the height of the stabilising mass above the ground may optionally be in the range 0.05 to 0.35 kg.m2. More particularly, it may be in the range of 0.05 to 0.2 kg.m2.

[0024] In some implementations, when the steering column is orientated for motion straight forwards, the centre of gravity of the stabilising mass is located rearwardly of the steering axis. The stabilising mass may then be rigidly coupled to the steering column. The stabilising mass may be rigidly and directly connected to the steering column and / or the handlebar of the vehicle.

[0025] The stabilising mass may be an elongate structure. For example, it may include an elongate body having a constant cross-section. The elongate body may be in the form of a bar or tube.

[0026] The stabilising mass may include a mounting coupling at each end. The mounting couplings may be configured to couple the stabilising mass to the steering column or handlebar of the vehicle.

[0027] The stabilising mass may comprise separate mass and support components, with the support component(s) carrying the mass component. For example, the support component may be tubular, with the mass component located within the tube. The mass component may be provided by a volume of material (such as lead) cast within the tube. The mass component may be spaced from the ends of the tube, so that it is spaced from the steering column in use. The mass component may be located in a portion of the tube furthest from the steering column in use, in order to increase the spacing of the centre of gravity of the mass from the steering axis.

[0028] In some examples, the stabilising mass may be integrally formed.

[0029] The vehicle body may lie in a vehicle reference plane which includes the steering axis and the centre of gravity of the stabilising mass may lie on the vehicle reference plane when the front wheel is orientated in a straight forward direction.

[0030] In some examples, when the steering column is orientated for motion straight forwards, the centre of gravity of the stabilising mass is located forwardly of the steering axis. The stabilising mass is coupled to the steering column via a coupling arranged such that the centre of gravity of the stabilising mass is able to rotate about an upright rotational axis that is fixed relative to the frame of the vehicle. Rotation of the stabilising mass about the rotational axis in one direction causes a torque to be exerted on the steering column in the opposite direction. In such implementations, a gear mechanism may be coupled between the stabilising mass and the steering column such that, when the vehicle experiences a roll acceleration to one side, the inertia of the stabilising mass causes a torque to be exerted on the steering column via the gear mechanism. The gear mechanism is arranged so that the torque acts in a direction which urges the front wheel to turn towards the one side so as to counter the roll motion.

[0031] The upright rotational axis of the stabilising mass may be parallel with the steering axis.

[0032] Brief description of the drawings

[0033] Examples of the present disclosure will now be described with reference to the accompanying schematic drawings, wherein:

[0034] Figures 1 and 2 show side views of electric scooters according to examples of the present disclosure;

[0035] Figures 3 to 5 show side views of an upper part of an electric scooter according to further examples of the present disclosure;

[0036] Figure 6 is a side view of an electric scooter illustrating suitable locations for the stabilising mass;

[0037] Figure 7 is a plan view of the handlebars of a bicycle according to a further example of the present disclosure; and

[0038] Figure 8 is a side view of an electric scooter according to another example of the present disclosure.

[0039] Detailed description

[0040] Figure 1 shows an electric scooter 2 which has been modified in accordance with the present disclosure. The scooter has a rigid body 4 including a horizontal footplate 6. A rear wheel 8 is rotatably coupled to the rear end of the rigid body 4. A front wheel 10 is rotatably coupled to the lower end of a steering column 12. The steering column is rotatable relative to the rigid body 4 about a steering axis 14. A handlebar 16 is provided at the upper end of the steering column.

[0041] References herein to the front wheel turning to one side indicate that the steering column rotates so as to move the front portion of the wheel towards that side.

[0042] A stabilising mass 20 (of mass M) is fixedly mounted to the top of the steering column 12 on a lever arm 22 (of length x), behind the axis 14 of the steering column. The height of the mass above the ground is h.

[0043] When the scooter is moving forwards and starts to roll to the right, the inertia of the mass causes it to apply a steering torque which urges the front wheel to turn to the right, and the resulting increase in path curvature generates a lateral force that counteracts the initial roll. This stabilises the roll mode. The equivalent response applies to a roll to the left.

[0044] The gain of the system is nominally M.x.h, but it is also a function of tyre and steering characteristics, rider mass, and the overall geometry of the vehicle. The gain may be selected to provide a desired combination of stability and control. The torque generated in the steering system is in addition to any self-centring steering moment due to caster angle and caster trail and so counteracts the roll.

[0045] The value of M.x.h may for example be in the range of 0.05 (or 0.1 or 0.15) to 0.35 kg.m2. More particularly, it may be in the range of 0.05 (or 0.1 or 0.15) to 0.2 kg.m2.

[0046] An alternative implementation to that of Figure 1 is shown in Figure 2. In this example, the stabilising mass 24 is elongate and has a generally U-shaped configuration, with its upper and lower ends 32, 34 fastened to the steering column 12, for example by welding. In another example, the ends of the stabilising mass may be fastened to the steering column by respective mounting couplings which may allow the stabilising mass to be detached from the steering column.

[0047] The stabilising mass 24 has a three-part construction. A central section 25 is formed of a solid rod of material, such as steel. It is connected at each end to first and second support sections, 26 and 27, respectively, the distal ends (32, 34) of each support section being fastened to the steering column 12. The support sections may be formed of a tubular section of a material such as steel. The support sections may be welded to the central section.

[0048] The stabilising mass may be made of a single piece of rod or tube of a material of sufficient density for the rod or tube itself to provide the required mass. For example, it may be formed of steel. Alternatively, the stabilising mass may be in the form of a block of a relatively dense material, such as lead, located within a tube formed of another material, such as aluminium.

[0049] Figures 3 to 5 illustrate variations of the stabilising mass construction. Each of these Figures shows a side view of an upper portion of the vehicle steering column 12. In the example shown in Figure 3, the stabilising mass 24’ is in the form of a tube 28 containing a block of material 29. The tube may be formed of steel, with a block consisting of lead cast into the tube, for example. The use of a higher density material than the tube to form the block enables the stabilising mass 24’ to be configured such that its centre of gravity is higher, as the block 29 is more localised and therefore shorter in the vertical direction for a given mass. A higher centre of gravity means that a lower mass of material may be used to provide the same stabilising effect. This in turn makes the vehicle as a whole lighter and reduces the cost of fabricating the stabilising mass.

[0050] In the further variation shown in Figure 4, tube 28’ has a larger diameter than the tube 28 shown in Figure 3. This again enables the stabilising mass 24” to be configured such that its centre of gravity is higher. Figure 5 shows another implementation, in which the stabilising mass 24”’ includes a central section 25’ in the form of a cast iron or cast steel piece of material. The central section has stubs 30 and 31 which are brazed to respective support sections 26’ and 27’ formed of steel tube, for example. The support sections may be formed of straight steel tubes, avoiding the need to bend lengths of tube in the construction process.

[0051] Figure 6 shows suitable locations for the centre of gravity of a stabilising mass provided rearwardly of the steering column. Dashed line 40 indicates the outline of a typical rider of the scooter for the purposes of illustration.

[0052] The height, h, of the stabilising mass above the ground may be at least 0.1m or more particularly at least 0.5m or 1.0m or more. It may be desirable for the stabilising mass to be located at a height close to, but not significantly greater than, the height of the vehicle (or more specifically its handlebar(s)) and so its height above the ground may not exceed 1.25m or 1.5m for example. The higher the mass, the smaller the mass needed to achieve a given value of M.x.h.

[0053] The distance between the centre of gravity of the stabilising mass and the steering axis 14, namely distance x, may for example be up to 0.25m. Greater distances may be impractical in some cases as they may cause the stabilising mass to impede the rider. In some examples the distance x may be 0.2m or less, or 0.15m or less. The minimum spacing from the steering axis may be around 0.02m or around 0.1m.

[0054] The mass of the stabilising mass, M, may be in the range of 0.2 to 5.0kg, or more particularly between 0.5 and 2.0kg.

[0055] For example, the height, h, may be in the range of 0.5m to the handlebar height, distance x in the range of 0.1 to 0.2m and mass M in the range of 0.5 to 2.0kg. More particularly, the value of M.x.h may in addition be in the range of 0.05 to 0.2 kg.m2. A further implementation shown in Figure 7. It shows a rod or tube 41 with its ends 32 and 34 attached to the handlebars 36 of a bicycle 38. The rod or tube extends rearwardly from the handlebars.

[0056] Another example of the present disclosure is shown in Figure 8. In this case, the centre of gravity of the stabilising mass 50 is located ahead of the steering axis 14. The mass is connected to a rotatable shaft 52 by a lever arm 54. The shaft is rotatable relative to, and carried by, a steering column shroud 56. The shroud is fixedly attached to the rigid frame 4 of the scooter, and the steering column 12 rotates within the shroud. The shaft 52 is in turn coupled to the steering column 12 via a gear mechanism 58. The gear mechanism is arranged such that rotation of the shaft in one direction causes the gear mechanism to exert a torque on the steering column in the opposite rotational direction.

[0057] When the scooter shown in Figure 8 experiences a roll acceleration to one side, the inertia of the stabilising mass 50 causes it to move relative to the vehicle frame towards the other side. The gear mechanism acts to convert the resulting torque on the shaft into a torque on the steering column in the opposite direction, thereby turning the front wheel towards the one side so as to counter the roll motion.

[0058] The parameters M, x and h may fall within the same ranges for the configuration shown in Figure 8 with the stabilising mass mounted ahead of the steering axis as for implementations with the stabilising mass mounted rearwardly of the steering axis, as discussed above. The gain the stabilising mass system will also depend on the gear ratio of the gear mechanism, with the gain depending on M.x.h.r, with “r” being the gear ratio. The gear ratio may be equal to the number of teeth on the steering column 12 divided by the number of teeth on the shaft 52.

[0059] The implementation shown in Figure 8 may be particularly suitable for a motorbike, in which the steering headstock is relatively high and the fuel tank is mounted just behind it, making it more practical to mount the stabilising mass ahead of the steering axis. It will be appreciated that references herein to perpendicular or parallel relative orientations and the like are to be interpreted as defining perpendicular or parallel relationships between components within practical tolerances.

Claims

Claims1. A vehicle including: a vehicle body; an upright steering column having a front wheel rotatably coupled to its lower end, wherein the steering column is rotatable relative to the vehicle body about a steering axis; and a stabilising mass fixedly coupled to the steering column, the mass being in the range of 0.2 to 5.0kg, wherein the centre of gravity of the stabilising mass is spaced from the steering axis by a distance in the range of 0.02 to 0.25m, and at a height above the ground in the range 0.1 to 1.5m, and the stabilising mass is coupled to the steering column such that, when the vehicle experiences a roll acceleration to one side, the inertia of the stabilising mass causes a torque to be exerted on the steering column in a direction which urges the front wheel to turn towards the one side so as to counter the roll motion.

2. A vehicle of claim 1, wherein the product of the magnitude of the stabilising mass, the distance between the centre of gravity of the stabilising mass and the steering axis, and the height of the stabilising mass above the ground is in the range 0.05 to 0.35 kg.m2.

3. A vehicle of claim 1 or claim 2 wherein, when the steering column is orientated for motion straight forwards, the centre of gravity of the stabilising mass is located rearwardly of the steering axis.

4. A vehicle of claim 3, wherein the stabilising mass is rigidly coupled to the steering column.

5. A vehicle of claim 3 or claim 4, wherein the stabilising mass comprises an elongate body.

6. A vehicle of any preceding claim, wherein the stabilising mass has a mounting coupling at opposite ends.

7. A vehicle of any preceding claim, wherein the stabilising mass comprises separate mass and support components, with the support component carrying the mass component.

8. A vehicle of any preceding claim, wherein the stabilising mass is integrally formed.

9. A vehicle of any of claims 1 to 7, wherein the stabilising mass comprises a battery for powering the vehicle.

10. A vehicle of claim 1 or claim 2 wherein, when the steering column is orientated for motion straight forwards, the centre of gravity of the stabilising mass is located forwardly of the steering axis, and the stabilising mass is coupled to the steering column via a coupling arranged such that the centre of gravity of the stabilising mass is able to generate a torque about an upright rotational axis, and rotation of the stabilising mass about its rotational axis in one direction causes a torque to be exerted on the steering column in the opposite direction.

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